Ostomy appliance with a filter outlet opening covered by a flap

ABSTRACT

An ostomy appliance having a front wall and a rear wall of flexible material forming a bag, the rear wall having an inlet opening into the bag by which waste material can enter the bag, at least one of the walls having a vent through which gas may escape from the bag, a filter covering the vent and having an outlet opening, and a flap sealed at only one end thereof to the wall so as to be pivotally movable in the plane of the wall from a first position in which the flap is attached to the wall and covers the outlet opening, to a second position in which the flap is shifted to one side so as to be offset from the first position such that the filter outlet opening is at least partially open.

This is a nationalization of PCT/DK03/00065 filed Feb. 3, 2003 andpublished in English.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ostomy appliance comprising adeodorising filter, in particular ostomy bags.

In connection with surgery for a number of diseases in thegastrointestinal tract a consequence is, in many cases, that the patientis left with a stoma such as a colostomy, an ileostomy or an urostomy inthe abdominal wall for the discharge of the effluents or waste productsof the body, which are conveyed through the colon, the ileum or theureter. The discharge of visceral contents including intestinal gasescannot be regulated at will, and for that purpose the opening may beclosed with a closure means, e.g. a tampon or a magnetic closure, or thepatient will have to rely on an appliance to collect the materialemerging from such opening in the form of a receiving bag which is lateremptied and/or discarded at suitable times.

Ostomy appliances are well known. Such appliances may be two-piece orone-piece appliances. In both types of appliances, an adhesive wafer isattached to the wearer's skin. In case of a one-piece appliance, areceiving member or bag is attached to the adhesive wafer. In case of atwo-piece appliance, the adhesive wafer forms part of a body side memberand a receiving bag is attached releasably to the body side ostomymember for receiving exudates from the stoma.

When using one-piece appliances, the whole appliance, including theadhesive skin barrier securing the appliance to the skin is normallyremoved and replaced by a fresh appliance. When using two-pieceappliances, the body side member is left in place up to several days,and only the receiving bag attached to the body side member is replaced.

The discharge of flatus, measured in volume, may exceed the discharge ofsolid and liquid faecal matter by many hundred percent and thereforethere is usually the need for the continuous or frequent venting of theintestine or the collecting bag. Normally the flow of flatus isdeodorised with a suitable filter. Commonly the active filter ispowdered active carbon, which absorbs H₂S being the principal componentof the smell of flatus.

In connection with the use of filters there is often a well-known needof measures for effectively preventing blocking of the inlet opening offilters of ostomy appliances. When the inlet opening of the filter isblocked, the gas discharged into the ostomy appliance cause ballooningof the bag being highly undesirable for several reasons.

Ballooning will be embarrassing for the user as the bag will bulge andthere is an increased risk of leakage being unacceptable for the user.

However, it has been found in practice that for some ostomates having avery low production of flatus there is a considerable risk that air isvented more quickly from the bag through the filter than the dischargeof gas into the bag and hence, a vacuum-like condition is produced inthe bag. The consequence may be that due to adhesion between the wallsof the receiving bag there is a considerable risk that visceral contentsreaching the opening of the stoma will not immediately be able toseparate the walls and “fall” into the bottom of the receiving bag butwill rather stay and block the entrance to the bag. This situation ishighly undesirable as faecal matter may be pressed against the areaaround the stoma and even beneath the adhesive wafer securing the ostomyappliance to the abdominal wall creating a risk of leakage and havingaggressive influence on the skin, or even upwards against the inletopening of a filter of the bag which will again further increase therisk of blocking of the inlet of the filter which again may result inballooning and even leakage.

2. Description of the Related Art

At present an ostomate may try to avoid this situation usingcommercially available separate adhesive labels that may be applied soas to cover the outlet opening of the filter partly or fully. Theseseparate filter labels are, however, not 100% sealing as their primaryfunction is to protect the filter against influence of water whilebathing and furthermore, such a label can only be used once. Thus, theostomate must always carry a minor supply of labels in order to securethe collecting bag against blocking as it is always necessary from timeto time to vent the bag in order to avoid ballooning.

European Patent No. EP 0 535 801 discloses an ostomy bag which has twovents one of which is filtered and the other of which is unfiltered. Anadhesive strip is used to seal the vents and can be peeled back to openthem so that by pulling the walls of the bag apart, air is drawn intothe bag. The vent is then closed to trap air in the bag and keep thefront wall away from the rear wall in the region of the opening in orderto avoid “pancaking”.

Published European Patent Application No. EP 0 985 390 discloses anostomy appliance having a filtered vent having a plurality of aperturesand adhesive sticker means which can be positioned to selectively exposeor cover one or more of the plurality of outlets to control the flowrate through the vent. The sticker means may consist of a number ofseparate sticker segments which can be peeled away to selectively exposeone or more exits under each segment. EP 0 985 390 is silent withrespect to a sticker having a surface which may be sealed releasably tothe wall enabling a placing of the sticker covering the outlet openingto a desired degree and also enabling a detachment and reattachment ofthe sticker according to the need which renders it possible to adapt theoutlet of gas from the bag according to the actual need by relocatingthe sticker so as to cover more or less of the outlet vent without beingdependent on disposable closures.

Thus, there is still a need of a closure which may prevent pancaking byallowing a 100% sealing of the outlet opening of the filter of an ostomyappliance and, at the same time, giving the option of allowing a minoramount of gas to pass out of an ostomy appliance according to needwithout having to rely on the presence of a supply of disposableclosures which may only be used once and which must be disposed of in anacceptable manner.

SUMMARY OF THE INVENTION

The invention relates to an ostomy appliance comprising a front wall anda rear wall of flexible material forming a bag, the rear wall having aninlet opening into the bag by which waste material can enter the bag andat least one of the walls having one or more vents through which gas mayescape from the bag and having a filter covering said vent and having anoutlet opening, wherein the appliance is provided with a flap having asurface being sealable to the wall in a manner in which the flap coversthe outlet opening and furthermore being sealable to the wall in amanner in which the flap is shifted sideways leaving the outlet openingof the filter partly or fully open.

The invention further relates to a device for controlling the venting ofgas from an ostomy appliance and to a method of controlling the ventingof gas from an ostomy appliance in order to prevent “pancaking” of theostomy appliance and, at the same time, giving the option of allowing aminor amount of gas to pass out of the ostomy appliance according toneed to avoid ballooning.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is disclosed more in detail with reference to the drawingsin which:

FIG. 1 shows a section of an embodiment of an appliance of the inventionhaving a controlling device of the invention in the open state, seenfrom the side of the wall having a vent;

FIG. 2 shows the embodiment of FIG. 1 having the controlling device in aclosed state;

FIG. 3 shows a section of another embodiment of an appliance of theinvention having a controlling device of the invention in the openstate, seen from the side of the wall having a vent;

FIG. 4 shows the embodiment of FIG. 3 having the controlling device in aclosed state;

FIG. 4A is an end view of the flap taken along line 4A-4A of FIG. 4;

FIG. 5 shows a section of yet another embodiment of an appliance of theinvention having a controlling device of the invention in the openstate, seen from the side of the wall having a vent; and

FIG. 6 shows the embodiment of FIG. 5 having the controlling device in aclosed state.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The present invention relates to an ostomy appliance comprising a frontwall and a rear wall of flexible material forming a bag, the rear wallhaving an inlet opening into the bag by which waste material can enterthe bag and one of the walls having one or more vents through which gasmay escape from the bag and having a filter covering said vent andhaving an outlet opening, wherein the appliance is provided with a flaphaving a surface being sealable to the wall in a manner in which theflap is covering the outlet opening of the filter and furthermore to bea sealed to the wall in a manner wherein the flap is shifted to the sideso that outlet opening of the filter is partially or fully open whichappliance is characterised in that wherein one end of the flap is sealedto the wall in a manner allowing a pivoting of the flap in the plane ofthe wall and that the flap has a surface which may be releasably sealedto the wall.

In a preferred embodiment of the invention, the flap is provided with ahole of at least the same diameter as the outlet opening of the filterand said flap being secured to the wall in a flexible manner allowingthe surface of the flap to be sealed to the wall in a manner in whichthe hole of the flap is aligned with the outlet opening of the filterand furthermore to be a sealed to the wall in a manner wherein the holeof the flap is shifted to the side so that outlet opening of the filteris sealed partially or fully. This embodiment is preferably deliveredfrom the manufacturer in a condition in which the hole of the flap isaligned with the outlet opening of the filter enabling the user toobtain the benefit of the present invention and, at the same time,enables a conventional use of the ostomy appliance.

The hole may be circular or elongated such as rectangular or oval givingthe options of a finer controlling of the flow according to the actualneed. The longest dimension of such elongated hole is preferably in thegeneral direction of shifting the flap.

It is also contemplated that the hole may have other shapes such askeyhole or triangular shape.

The ostomy appliance of the invention allows a 100% sealing of theoutlet opening of the filter of an ostomy appliance and, at the sametime, gives the option of allowing a minor amount of gas to pass out ofan ostomy appliance according to need and the sealing flap may bepositioned and repositioned several times eliminating the need ofhandling a number of disposable closures. It is preferred that the areaof the wall around the outlet opening of the filter is provided with asurface layer having a surface prepared for repeated attachment anddetachment of an adhesive surface and that the surface of the flapfading the wall is provided with an adhesive being suitable for safeattachment of the flap to the surface enabling a temporary venting ofthe bag and resealing according to need during the service time of thebag. The surface layer may e.g. be glued or welded to the wall.

The surface layer and the flap may for example be moulded in awater-repellent cellular plastics material, such as ethylene vinylacetate (EVA) or polyurethane (PUR), preferably with closed cells sothat the cellular plastic material does not absorb liquid; or be madefrom a suitable plastics material such as the materials suitable forproduction of ostomy appliances. It only has to be ensured that theforce needed for peeling the flap from the adhesive is greater that theforce needed for peeling the adhesive from the surface layer.

The fact that the end of the flap is sealed to the wall in a mannerallowing a pivoting of the flap in the plane of the wall enables asimple means for partially sealing the outlet opening in accordance withthe actual need of venting.

The flap of the ostomy appliance of the invention suitably comprises abacking layer, optionally a carrier layer for the adhesive, and anadhesive layer.

In a preferred embodiment of the invention the backing layer is anintegrated part of a woven or non-woven outer layer of the applianceenabling a simple securing of the flap to the appliance. Using thisembodiment it is simple to provide the pivoting as the flap may be cuthaving a considerable length which, combined with the pliability of thewoven or non-woven layer, will allow a considerable displacement of theend of the flap in the plane of the wall.

In another embodiment of the invention the carrier layer of the flap andthe surface layer of the wall are integrated and united having aconnecting zone forming a hinge. This embodiment is especially suitablefor use in connection with ostomy appliances not having an outer layerof woven or non-woven material or appliances for a simple enabling ofthe present invention.

A simple manner of achieving this is by enabling a pivoting in case of ahinged flap to have a zone of bending in which the length of theconnection between the two parts is considerably smaller than the widthof the flap. The length of such a zone may e.g. be from 2 to 10millimeters, more preferred from 3 to 6 millimeters, depending of thestrength and flexibility of the material of the flap.

The ostomy appliance according to the invention may be adapted for usetogether with an ostomy body side member (2-piece appliance) wherein thereceiving bag is provided with coupling means for releasable securing tomatching coupling means placed on the ostomy body side member andwherein the inlet opening is adapted for alignment with a hole of theostomy body side member for receiving a stoma.

The ostomy appliance according to the invention may, as an alternative,be adapted for use directly (1-piece appliance) in which case the bag isprovided with an adhesive wafer for securing the receiving bag to theuser's skin, said bag and wafer having an inlet opening for receiving astoma.

As indicated above, an ostomy-receiving bag of the invention is providedwith a vent. Such bags may be closed bags but it is also contemplatedthat an ostomy-receiving bag of the invention may be in the form of anopen bag.

The ostomy appliance itself comprising front and rear walls sealedtogether along the rim and provided with an inlet opening may be made inanalogy with and from materials conventionally used for the preparationof ostomy appliances.

Such materials are suitably films composed of any suitable material,which is heat sealable and sufficiently impervious for unpleasant odourssuch as polyolefin films or combinations of such films, e.g.polyethylene or a coextrudate of polyethylene and polyvinylidenechloride.

An ostomy body side member for use together with an ostomy-receiving bagaccording to the invention may be produced from standard materialsnormally used for preparation of disposable ostomy and wound care andincontinence devices.

Thus, the adhesive wafer for a body side member or of a 1-piece ostomyappliance bag according to the invention may be made from a medicalgrade barrier adhesives known in the such as the formulation beingdisclosed, for example in U.S. Pat. Nos. 4,367,732, 5,051,259 or5,714,225. For a 2-piece ostomy appliance according to the invention thebody side member and the receiving bag are provided with matchingcoupling means.

The coupling means for use in connection with the present invention maybe any suitable coupling means known per se for coupling of ostomy baseplates to ostomy collecting bags, e.g. a mechanical coupling such asmatching coupling rings such as the coupling rings disclosed in WO91/01118 and WO 91/01119 or WO 94/18919 or matching flanges for adhesiveconnection of the type disclosed in U.S. Pat. No. 5,800,415.

Suitable materials for use as woven or non-woven outer layer aremoisture resistant woven or non-woven sheet materials, which may beunited with materials conventionally used in the production of ostomyappliances. Such materials are preferably compatible with the materialsused for the preparation of ostomy appliances allowing a simpleassembling using welding e.g. using heat, laser or high frequencywelding. Preferred materials for use in the present invention are wovenor non-woven materials of polyethylene, polypropylene or a polyester,which are thermoformable and may easily be welded to the wall of the bagusing conventional techniques.

Preferred materials for use as surface layers for walls of appliances ofthe invention are sheet materials of the kinds mentioned above which maybe united with materials conventionally used in the production of ostomyappliances.

The adhesive used for adhering the flap to the wall may be any suitableadhesive and is preferably an adhesive also having wet tack propertiesin order to ensure a proper function also in a humid environment, e.g.when bathing, which will prolong the expected service time of theappliance as an incidental wetting would not compromise theadhesiveness.

In a second aspect the invention relates to a device for controlling theventing of gas from an ostomy appliance comprising a front wall and arear wall of flexible material forming a bag, the rear wall having aninlet opening into the bag by which waste material can enter the bag andat least one of the walls having one or more vents through which gas mayescape from the bag and having a filter covering said vent and having anoutlet opening, said device being in the form of a flap being secured tothe wall in a manner in which the flap is covering the outlet opening ofthe filter and furthermore to be a sealed to the wall in a mannerwherein the flap is shifted to the side so that outlet opening of thefilter is partially or fully open which device is characterised in thatone end of the flap is sealed to the wall in a manner allowing apivoting of the flap in the plane of the wall and that the flap has asurface which may be releasably sealed to the wall.

The device of the invention enables a control of the venting of gas froman ostomy appliance having one or more vents through which gas mayescape from the bag and having a filter covering said vent and having anoutlet opening and enables prevention of “pancaking” of the ostomyappliance for ostomates having a very low production of flatus having aconsiderable risk that a vacuum-like condition is produced in the bagdue to air being vented more quickly from the bag through the filterthan the discharge of gas into the bag by enabling a total closure ofthe outlet opening and, at the same time, giving the option of allowinga minor amount of gas to pass out of the ostomy appliance according toneed to avoid ballooning.

In a third aspect the invention relates to a method of controlling theventing of gas from an ostomy appliance for preventing “pancaking” ofthe ostomy appliance and, at the same time, giving the option ofallowing a minor amount of gas to pass out of the ostomy applianceaccording to need to avoid ballooning comprising applying an ostomyappliance comprising a front wall and a rear wall of flexible materialforming a bag, the rear wall having an inlet opening into the bag bywhich waste material can enter the bag and at least one of the wallshaving one or more vents through which gas may escape from the bag andhaving a filter covering said vent and having an outlet opening, whereinthe appliance is provided with a flap being sealable to the wall in amanner in which the flap is covering the outlet opening of the filterand furthermore to be a sealed to the wall in a manner wherein the flapis shifted to the side so that outlet opening of the filter is partiallyor fully open, which method is characterised in that an ostomy applianceis used in which one end of the flap is sealed to the wall in a mannerallowing a pivoting of the flap in the plane of the wall and that theflap has a surface Which may be releasably sealed to the wall.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention is now explained more in detail with reference to thedrawings showing preferred embodiments of the invention. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

Reference is made to FIGS. 1 and 2 showing a section of an embodiment ofan appliance of the invention having a controlling device of theinvention in the open state and closed state, respectively, seen fromthe side of the wall having a vent. The section shows the top of anostomy appliance comprising a front wall 12 and a rear wall 1 of aflexible material forming a bag, the rear wall having an inlet opening 2into the bag by which waste material can enter the bag and at least oneof the walls having one or more vents 14 through which gas may escapefrom the bag such that a wall with a vent may be referred to herein as avented wall. The vented wall includes a filter 16 covering the vent andhaving a filter outlet opening 3. The appliance is provided with aflexible flap 4 that is secured in one end 5 to the wall of theappliance and has a surface that is releasably sealable to the wall. Theflap is an integrated part of a woven or non-woven outer layer of theappliance enabling a simple securing of the flap to the appliance. Inthis embodiment the flap is cut having a considerable length and anarrow zone at the end of the flap being secured to the bag enabling apivoting of the flap which, combined with the pliability of the woven ornon-woven layer, allows a considerable displacement of the free end ofthe flap in the plane of the wall of the bag for being attached to thewall either beside or covering the filter outlet opening leaving thesame partly or fully open as shown in FIG. 1 or closed as shown in FIG.2. As shown in these two figures, pivoting of the flap displaces thefree end of the flap from a position beside or adjacent the filteroutlet opening (FIG. 1) to a position covering the filter outlet opening(FIG. 2) such that these two positions of the flap are not concentricwith one another but offset. Furthermore, FIG. 1 shows an adhesive wafer6 for securing the appliance to the skin of the user as well as a seam 7sealing then rims of the front and rear walls forming a bag.

FIGS. 3, 4 and 4A show another embodiment of an appliance of theinvention corresponding to the device shown in FIGS. 1 and 2 but havinganother controlling device of the invention in the open state and closedstate, respectively, seen from the side of the wall having a vent. Inthese figures corresponding reference numbers refer to correspondingelements. In this embodiment the venting controlling device of theinvention is in the form of a flap 4 having a backing layer 18, which isprovided with a carrier layer 20 being integrated with a surface layer 8placed on the wall and having a connecting zone 9 forming a hinge. Thecarrier layer 20 has an adhesive surface 22. In this case, a pivoting isenabled by providing a zone of bending forming the hinge in which thelength of the connection between the two parts is considerably smallerthan the width of the flap. Like the embodiment of FIGS. 1 and 2, theflaps pivots substantially in the plane of the wall from a positionbeside or adjacent the filter outlet opening (FIG. 3) to a positioncovering the filter outlet opening (FIG. 4) such that the two positionsof the flap are not concentric with one another, but offset. In thisembodiment, the bag is provided with a woven or non-woven outer layer 10provided with an opening leaving space for the controlling device.

FIGS. 5 and 6 show another embodiment of an appliance of the inventioncorresponding to the device shown in FIGS. 3 and 4 but having anothercontrolling device of the invention in the open state and closed state,respectively, seen from the side of the wall having a vent. In thesefigures corresponding reference numbers refer to corresponding elements.In the embodiment shown in FIGS. 5 and 6, the flap is provided with ahole 11 of at least the same diameter as the filter outlet opening 3.The flap is secured to the wall in a flexible manner allowing thesurface flap to be sealed to the wall in a manner in which the hole ofthe flap is aligned with the filter outlet opening of the filter andfurthermore to be sealed to the wall in a manner wherein the hole of theflap is shifted to the side so that the filter outlet opening of thefilter is sealed partially or fully.

The invention being thus described, it will be apparent that the samemay be varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be recognized by one skilled in the art areintended to be included within the scope of the following claims.

1. An ostomy appliance comprising a front wall and a rear wall offlexible material forming a bag, the rear wall having an inlet openinginto the bag by which waste material can enter the bag, at least one ofthe walls of the bag having at least one vent through which gas mayescape from the bag so as to be a vented wall, a filter covering saidvent and having a filter outlet opening, and a flap secured at only oneend thereof to said vented wall adjacent said filter outlet opening,said flap being pivotally movable between a first position in which saidflap is releasably sealed to the wall and covers said filter outletopening, and a second position in which said flap, by pivoting on saidone secured end, is shifted to one side so as to be non-concentric withsaid first position and releasably sealed to the vented wall adjacentsaid filter outlet opening, said flap in said second position causingsaid filter outlet opening to be partially or fully open.
 2. The ostomyappliance as claimed in claim 1, wherein the flap includes a hole havinga diameter at least as large as a diameter of said filter outletopening, said hole and said filter outlet opening being out of alignmentwhen the flap is in said first position, and said hole being at leastpartly aligned with said filter outlet opening such that the filteroutlet opening is at least partially open when the flap is in saidsecond position.
 3. The ostomy appliance as claimed in claim 1, whereinthe area of the vented wall around the filter outlet opening is providedwith a surface layer having a surface prepared for attachment anddetachment of an adhesive surface and that a surface of the flap facingthe vented wall is provided with such an adhesive.
 4. The ostomyappliance as claimed in claim 1, wherein the flap includes a backinglayer and an adhesive layer.
 5. The ostomy appliance as claimed in claim4, wherein said flap includes a carrier layer for the adhesive layer. 6.The ostomy appliance as claimed in claim 4, wherein the backing layer isan integrated part of a non-woven outer layer of the appliance.
 7. Theostomy appliance as claimed in claim 3, wherein the flap includes acarrier layer, said carrier layer and the surface layer of the ventedwall being integrated and united, having a connection zone forming ahinge.
 8. The ostomy appliance as claimed in claim 1, wherein the areaof the vented wall around the filter outlet opening is provided with asurface layer prepared for adhesive attachment and detachment of saidflap.
 9. The ostomy appliance as claimed in claim 1, wherein said flapis secured to the vented wall at a connection zone forming a hinge. 10.An ostomy appliance comprising a front wall and a rear wall of flexiblematerial forming a bag, the rear wall having an inlet opening into thebag by which waste material can enter the bag, at least one of the wallsof the bag having at least one vent through which gas may escape fromthe bag so as to be a vented wall, a filter covering said vent andhaving a filter outlet opening, and a flap secured at only one endthereof to said vented wall adjacent said filter outlet opening, saidflap having a hole therein with a diameter at least as large as adiameter of said filter outlet opening, said flap being pivotallymovable between a first position in which said flap is releasably sealedto the vented wall with said hole and said filter outlet opening beingin alignment such that said filter outlet opening is open, and a secondposition in which said flap, by pivoting on said one secured end, isshifted to one side so as to be non-concentric with said first positionand releasably sealed to the wall, said hole being at least partly outof alignment with said filter outlet opening such that the filter outletopening is at least partially closed when the flap is in said secondposition.
 11. The ostomy appliance as claimed in claim 10, wherein theflap includes a backing layer and an adhesive layer.
 12. The ostomyappliance as claimed in claim 11, wherein said flap includes a carrierlayer for the adhesive layer.
 13. The ostomy appliance as claimed inclaim 11, wherein the backing layer is an integrated part of a non-wovenouter layer of the ostomy appliance.
 14. The ostomy appliance as claimedin claim 10, wherein the area of the vented wall around the filteroutlet opening is provided with a surface layer configured for directattachment and detachment of said flap when releasably sealing said flapto said vented wall.
 15. The ostomy appliance as claimed in claim 14,wherein said flap includes a carrier layer integrated or united withsaid surface layer and having a connection zone forming a hinge.
 16. Theostomy appliance as claimed in claim 10, wherein said flap is secured tothe vented wall at a connection zone forming a hinge.
 17. A method ofcontrolling the venting of gas from an ostomy appliance for preventingpancaking of the ostomy appliance and, at the same time, allowing aminor amount of gas to pass out of the ostomy appliance according toneed to avoid ballooning, said ostomy appliance having a front wall anda rear wall of flexible material forming a bag, the rear wall having aninlet opening into the bag by which waste material can enter the bag, atleast one of the walls having at least one vent through which gas mayescape from the bag so as to be a vented wall, a filter covering saidvent and having a filter outlet opening, and a flap secured at only oneend thereof to said vented wall adjacent said filter outlet opening soas to be pivotally movable in a plane substantially parallel to theplane of the vented wall, said method comprising the steps of: applyingthe ostomy appliance to an ostomate so that waste material from theostomate's stoma can enter the bag through the inlet opening; securingsaid flap in a first position in which said flap is releasably sealed tothe vented wall and covers said filter outlet opening; moving said flapin said plane substantially parallel to the plane of the vented wall toa second position in which said flap, by pivoting thereof on said onesecured end, is shifted to one side so as to be offset from said firstposition; and releasably sealing said flap to the vented wall in saidsecond position, said filter outlet opening being at least partiallyopen with said flap in said second position to allow venting of gasesfrom said ostomy appliance.
 18. The method as claimed in claim 17,wherein said step of securing said flap in the first position includesadhering an adhesive surface of said flap to a surface layer of saidvented wall adjacent said filter outlet opening.
 19. A method ofcontrolling the venting of gas from an ostomy appliance for preventingpancaking of the ostomy appliance and, at the same time, allowing aminor amount of gas to pass out of the ostomy appliance according toneed to avoid ballooning, said ostomy appliance having a front wall anda rear wall of flexible material forming a bag, the rear wall having aninlet opening into the bag by which waste material can enter the bag, atleast one of the walls having at least one vent through which gas mayescape from the bag so as to be a vented wall, a filter covering saidvent and having a filter outlet opening, and a flap secured at only oneend thereof to said vented wall adjacent said filter outlet opening soas to be pivotally movable, said flap having a hole therein with adiameter at least as large as a diameter of said filter outlet opening,said method comprising the steps of: applying the ostomy appliance to anostomate so that waste material from the ostomate's stoma can enter thebag through the inlet opening, said flap being secured in a firstposition in which said flap is releasably sealed to the vented walladjacent said filter outlet opening and said hole in said flap is inalignment with said filter outlet opening such that said filter outletopening is open to allow venting of gases from said ostomy appliance;moving said flap to a second position in which said flap, by pivotingthereof on said one secured end, is shifted to one side so as to benon-concentric with said first position; and releasably sealing saidflap to the vented wall in said second position, said hole in said flapbeing at least partly out of alignment with said filter outlet openingin said second position such that the filter outlet opening is at leastpartially closed.
 20. The method as claimed in claim 19, wherein saidstep of releasably sealing said flap in the second position includesadhering an adhesive surface of said flap to a surface layer of saidvented wall adjacent said filter outlet opening.
 21. The ostomyappliance as claimed in claim 1, wherein said flap is pivotally movablein a plane substantially parallel to the plane of said vented wall. 22.The ostomy appliance as claimed in claim 10, wherein said flap in saidsecond position is releasably sealed directly to said vented wall or toa surface layer provided on said vented wall for releasable sealing ofsaid flap.
 23. The ostomy appliance as claimed in claim 22, wherein saidsurface layer is glued or welded on said vented wall.
 24. The ostomyappliance as claimed in claim 1, wherein the area of the vented wallaround the filter outlet opening is provided with a surface layerconfigured for direct attachment and detachment of said flap whenreleasably sealing said flap to said vented wall.